This Wikipedia page provides a good review of patent terms in the US. Essentially the term is 20 years from the priority date for patents filed on or after June 8th, 1995 or the longer of 20 years from the priority date or 17 years from the grant date for patents filed before June 8th, 1995.

Unless there were extensions filed (I couldn't find any), the patent should have expired August 29 of 2014.